Process for making combustible gas



June 15, 1954 w. w. ODELL 2,681,273 PROCESS FOR MAKING COMBUSTIBLE GASFiled Aug. 23, 1947 2 Sheets-Sheet l FUEL HEAT EXCHANGER HYDRO\CARBONSTEAM ENRICHER 54 GAS M|XTURE FUEL ASH

nvenibr June 15, 1954 w. w. ODELL PROCESS FOR MAKING COMBUSTIBLE GASFiled Aug. 23, 1947 2 Sheets-Sheet 2 COMBUSTION PRODUCTS souo FUEL- 37 RE m w m M M S N E E Q a m T L A 4 2 M 2 O 5 m N P 5 2 a s f 1 .p a m I r1- a a c 7 2 4 9 a m A GAS MIXTURE was turned on. for a number of veryimportant reasons, in-

perature of the Patented June 15, 1954 UNITED STATES PATENT OFFICE2,681,273 PROCESS FOR MAKING COMBUSTIBLE GAS William W. Odell,Washington, D. 0., assignor to Standard Oil Devel opment CompanyApplication August 23, 1947, Serial No. 770,271 6 Claims. (01. 48-196)This invention relates to process and apparatus for making combustiblegas. It relates to the generation of gas for city distribution as wellas to the production of gas for industrial use.

In particular, it has to do with the gasification of coal, coke,lignite, char or a subdivided state, the particles being much smallerthan those commonly charged to a water gas generator in the ordinaryintermittent water gas process. The process operation of this ining ofthe fuel bed with air and steam in cycles good grade of gas and thatmany did not yield a difiiculties arose, including the tendency for thefuel to settle when the air was turned off and to resist completefluidization when the steam The cycle had to be Very short cluding thefact that the gases made during both the air blast and steam run periodsleft the generator at substantially the maximum temfuel bed causing avery appreciable carrying-away of heat from the which called forfrequent replenishing. A further hindrance to successful development ofthis making velocities or economic gas-making ve- 'locities of thegas-generating fluids in the genor gas pockets the fuel.

fluidized bed of fuel is below the ash softening 1 temperature, theoperation thus being continuous. My investigations of this operationshow that even in this case the gas made was not of "good quality untiladditional oxygen and steam were amounts and generator other solid fuelin mg fluid which may be air,

tion of the generator several hundred degrees centigrade above that inthe fuel bed; this was largely because it was not possible to maintain adeep bed without formation of gas pockets commonly referred to asslugging.

One of the objects of this invention is to eliminate the necessity ofusing straight oxygen to supply, by combustion reactions with carbon,the heat necessary for promoting the steam-carbon reactions. In thelatest development of the Winkler process at the close of the recentworld war, the amount of oxygen used, calculated as pure 02 per 1000cubic feet of gas made was approximately 14.5 to cubic feet, based onscrubbed gas still containing 10 percent of 002; the gas as generatedcontained appreciably more than 10 percent of CO2.

Another object is to economize heat energy and to make possible andfeasible the use of air to supply at least a part of the heatrequirements of the process by combustion reactions in the fuel bed.

Still another object is to make intermittent operation feasible andeconomical. Other objects will become evident by the followingdisclosures and claims.

The invention can best be described by ref erence to the figures withspecific examples of a few methods of operation.

Figure 1 depicts one type of generator in which the novel features ofthe process of this invention may be practiced; it is shown in elevationbut largely diagrammatically and as a flow diagram, and has a portion ofthe outer generator-wall cut away to show the interior in section. Thegenerator of this figure is particularly adapted for making water gas orenriched water gas intermittently in cycles.

Figure 2 shows a similar diagrammatic view of another embodiment of theinvention, being essentially a generator in which the process steps ofthis invention may be practiced with re-circulation features which aredescribed hereinafter.

In Figure 1 the generator I has upper expended regions 2 and Z-A, a gridmember 3 adjacent to the bottom, means for admitting air steam andoxygen with control valves 4, 5 and 6, respectively, and fixed spacedpacking regions A, C and D. Fuel hopper l supplies small size solid fuelto the generator through control valve 8' and auxiliary supplies ofsteam, combustion supportand vapor phase hydrocarbons may be fed to thegenerator through bustle pipe IS, the respective controlvalvesbeingenerator ing (1, i5 and i8. Gas offtake 9 at the top of the generatoris so connected that blast gases, largely products of combustion, may beremoved therefrom through valve 10, heat exchanger ii, and. offtake 12,whereas richer gas may be removed from 9 through conduit i3 and valve ii from which it may be conducted to a gas treat ing and handling systemnot shown. Means for introducing steam. and a carbureting fluid areshown by bustle pipe 22, conduit 23 and respec tive control valves 25and E i. Thermo-coupie 21 is suitably connected for indicatingtemperature in the bed of fluidized solid "fuel; the connections are notshown. The generator has a differential pressure recorder 28, a valve 2%for discharging finely divided solids, a valve ti! for introducing fueltherein through conduit. 3i, valve 33 for introducing a hydrocarbon inthe vapor phase, valve 3d for introducing a gas mixture, such as CO andH2, valve Iii-A for intro ducing fuel.

In Figure 2 the same system of numbering-has been employed as was usedwith reference to Figure I; however, additional numbers are employed onFigure 2 designating parts not shown in Figure 1 as follows:

A water jacket 354s provided in the upper portion of the generator-wall.which is connected by a steam conduit SEto-asteam drum or accumu lator.31' which later has a water leg 38 for supplying water to the waterjacket. Water is sup.- plied to the steam drum 3'! through valve 39 andsteam is discharged from 3i through valve 48. The combination of awater-cooled wall'adjacent an upper zone of the bed of fluidized solidsl'makes possible the cooling of the fluidized solids in the zoneadjacent thereto, and

designated F which in turn'hastens the rate of travel downwardly of thefluidized solidsin F into zone C. The-water in jacket 35 absorbs heatfrom the solids fluidized in zone F, which heat would normally belargely wasted, forming steam which is, or may be, utilized in thegas-making process. It isrecognized that it is not new to cool the wallof a hot surface by a water jacket, but the effect obtained in this caseis believed to be new; the solids fluidized in zone F are in freeebullient motion and make-possible a set of conditions includingeconomical-heat recovery which isnot possible so far as I am aware inany other system. c

EXAMPLE 1 Making water gas from fine size. coke, Ai-to inch meandiameter of particles, free from dust, by cyclic operation Referring toFigure 1, proceed asfollows: Supply the solid fuel to generator I byopening valve 8 until it reaches the level indicated by sightcock [9.Now place some ignited combustible matter in the base of the generatorthrough door 20 and then start air blasting, slowly atfirst, by partlyopening valve 4. Continue air. blasting and as it becomes clear thatcombustionis occurring in the bed of coke in the generator, as noted bythetemp'erature andthe composition of the combustion products now beingdischarged above through 9,15, H and i2, the rate of air blasting isincreased by further opening air valve d sothat the velocity of the airin zone A, basedon air at standard temperature and pressure andconsidering this zone as empty, is approximately 115 to? 2.5 feet persecond. At this velocity the'fuel solids will be fluidized in zone Aforming a bed ofmedium density, whereas the fuel solids'in the higherzone B will" form a bed of greater density.

bed density in zone largely consumed of the finely divided ash iscarried out of the This air blasting is continued until the fluidizedparticles in zones A and B have become heated to a temperature of theorder of 1900 to 2000 F. When this point is reached it will be foundthat the temperature of the packing in zone A is also heated toapproximately the same temperature. The air valve i is now slowly closedas steam valve 5 is opened and an up-steam run is now made, the watergas forrned being conducted out of generator I through offtake 3,conduit l3 and valve it and handled in a known manner. The velocity ofthe steam as it enters zone A is preferably as high as that of the air,whereby the velocity of the gas stream with excess steam as it passesupthrough zone A. is greater than the gas stream Under this conditionthe A is lower during the steam run than during the air-blasting periodand some of the fluidized fuel initially in zone A migrates to a higherlevel. The steam takes up heat from the packing inzone A- and therebybecomes; heated to a temperature of the. order of 2000" F. or a littlelower, and in this state it contacts the freely fluidized solid in zoneB where it reacts more completely'therewith forming watemgas. The majorreaction of carbon and steam in the during air blasting.

generator is as shownby the following equations:

More of reaction of Equation 1 ocoursdnzone A than in zone B and moreof=the=reaction of.Equation 2 occurs in zone B thanfini A, the resultbeing that high-grade water gas is produced, being chiefly CO+Hz with arelatively small amount of CO2. During. this operationheat is absorbedfrom the packing in zone A, its :mean temperature being lowered andheatis. given up by the hot gases passing'upwardly to-theipacking in zones Cand D and to the solid fuel fluidized therein. Thus, the gases passingout' through. 9 leave the generator relatively cool, that: is, below1800 F. in this example. The level of the fluidized solid fuel ingenerator i will be at L during the steamrun but immediately the steamrunis discontinued and air blasting again initiated'the level issomewhat lower. This change, to air blasting is made after thetemperature as indicated by means of thermocouple 2T is about l-200 to1300 F. as follows: turn steamvalve 501i slowly while simultaneouslyopening .air valve- 4 and after about 5 secondsclose valve Hand openii]. Fresh solid fuel may be introduced. continuously through valve 8but it is preferable usually to charge it during the air-blast periodunlessit contains valuable volatilizable products to be recovered, inwhich case it is preferable to charge the solid fuel during the steamrun. Thefresh fuel becomes preheated quite uniformly as, it

' descends downwardly into the gas-making, zones.

processes wherein the lumps are superficially outer surfacesonlyuntilthey are in gas making reactions. Most heated on theirgenerator during the steam run although'some passes out during the airblast. The cycle as described is repeated as desired.

A variation in the procedure outlined above,

which is particularly applicable to making gas for ammonia synthesis,is, as follows:

Blast the bed of solid fuel with air; asbefore,

then make a steam run as before only, duringgthis steam run allow someair to pass into the fuel bed with the steam by opening valve 8, the

valve I and open valve I 4.

thermocouple 27,

amount of air thus used being sufficient to provide the N2 required inmaking ammonia. Because of the small size of the solid fuel used the thebed. When maximum time is desired a further slight variation ofoperating procedure is made referring to Figure l as follows: Air blastthe ignited fuel as before by opening valve 4 and during at least aportion of this air-blasting period open air valve I6 and allow someair, but preferably less than that introduced through 4, to pass intothe generator through bustle pipe I5. some of the combustible gaspassing up into the lower stores heat in the fluidized fuel bed and inthe packing solids. Now close valve I6, then close air valve 4 and opensteam valve and then close Steam may now be admitted also through I5 byopening valve I I. In all cases the fresh solid fuel is fed to thegenerated by the air zone of. the bed and generator in sufficient amountto equal the fuel consumption.

EXAMPLE 2 Making producer gas from char, or low temperature cokeinitially sized about 3 3 to 4-inch particle mean we 1 First air blastthe ignited fuel by opening valve 4 until the fuel bed is at agas-making temperature approximately 1800 to 1900 F. Now pass a mixtureof air and steam up throughthe bed, maintaining fiuidization of the fuelby controlling the velocity of the gaseous stream through the bed and soproportioning the steam and air thus indicated by through a port for thepurpose, not shown in the figure,

is maintained at about 1750 F. to 1850 F. The steam and air thusintroduced may be admitted in admixture as through valves 5 and 6 orthrough 5 and 4 respectively. The gas formed is withdrawn or discharged,as made, through oiftake 9, conduit l3 and valve I4. The temperature inzone C will gradually rise and will finally approach as an upper limitthe temperature in zones A and B. For economic reasons it is desirableto introduced some steam into an upper portion of the fuel bed and thismay be done by opening valve IT either intermittently or allowing it toremain open sufficient to providethe required amount of steam. It willbe found that the producer gas made in this example will have a low CO2content, 8

The latter air burns a diameter and referring to Figgas production perunit of air admitted into B is increased. The temperature in the latterzone may be increased by increasing the airsteam ratio in the mixtureadded through 5 and.

does not occur when all of the solid fuel supplied through 8 fromreservoir 1 is sized mesh and finer; in that case the ash passes outoverhead entrained in the gas.

Modifications of operating details may be made within the confines ofExample 2 whereby the composition and calorific value of the gasgenerated may be altered. These modifications may include:

(a) Introducing some 02 with the steam and the bottom zone of the fuelbed.

(b) Introduction of oxygen with steam admitted through bustle pipe I5.

(0) Introduction of enricher, through valve 24 or I8. or both.

Benefits common to the use of preheated air and superheated steam in gasmaking also are but with the additional benefit derived from introducingit in as for example,

to 150 B. t. u. per cubic foot without adding depth is increased and asthe temperature in zone ized in a reaction zone,

enricher or using free oxygen and may be appreciably higher whenenricher is added. he noted that when enricher is introduced into zone Bit immediately contacts a large surface of hot fuel (fluidized,incandescent finely divided solid fuel), and is forthwith reacted withsteam and/or cracked. This is particularly true when the enricher iscomprised of hydrocarbon material.

EXAMPLE 3 Re-forming hydrocarbons and producing gas containingappreciable amounts of Hz and C0 This example involves the introductionof one or more than one hydrocarbon, such as methane, ethane, propane,butane, ethylene, propylene and the like, into a mass of highly heatedsolids, fluidalong with an oxidant of the class CO2, 02 and steam. Thedata and procedure are presented in this example with particularreference to the re-forming of natural gas comprising percent CH4 and 10percent ethane employing steam as the oxidant.

Referring to Figure l, ignited small-size coke, char or other suitablesolid fuel is blasted with air, while it is confined as a deep bed ingenerator I, by opening valve 4, the volume of air thus introduced intoI being suificient to fiuidize the solid fuel. The air valve IE is thenopened to introduce secondary air into the fuel bed through bustle pipe55. The products of combustion are passed out above through ofitake 9,conduit H),

exchanger I I and offtake I3. After about 3 minutes it will be foundthat the temperature in zones A and B approximate 2l00 to 1900 F. Theair valves 4 and it are now closed and simultaneously steam valve 5 isopened and then stack-gas valve I 0 isclosed simultaneously with theopening of gasyalve 14.

a bed of very low density in zone 7 Now naturalgas is introduced byopening valve. li -A, the" mixed steam and natural gas pass up'duringthis gas-making run into the bed from'beneath'it. The velocity of thegas stream in zone A during air blasting is approximately 2.2 feet persecond which produces A but a denser bed in zone 13. During theair-blasting period the packing in zone A becomes heated to about.

2000 F. and stores considerable heat energy. The natural gas and steam,initially the major components of the stream passing up through thefuel. bed during the gas-making period, are so proportioned that foreach 1000 cubic feet of nattotal gas used about 100 pounds of steam areintroduced therewith. The gas and steam are preferably preheated to atemperature above 500 The composition of the resulting gas issubstantially as follows:

Percent by vol.

CO2 8.4. CO H; 16.2 Hz. 68.5 CH4 5.9 Cal-Is 0.0 Na 1.0

The amount of carbon consumed during the gas-making run is calculated as1.8 pounds per 1000 cubic feet of gas made and the volume swell figuredon the basis of the natural gas used is 4.41'volumes from 1 volume ofnatural gas. The carbon burned during culated, was 7.8 pounds per 1000cubic feet of natural gas used. The total solid fuel used per 1000 cubicfeet of gas made, calculated as ash free, was 6.0 pounds. By increasingthe ratio of steam to natural gas in the feed the volume ratio of Hz toCO in the gas made is decreased and more water gas is made. The durationof the gas-making run is preferably longer than the airblasting period,and is 4 minutes in this example and the initial velocity of thesteam-natural gas mixture in zone A is less than 2.2 feet per second inorder to maintain a'denser bed in zones A and B, but particularly inzone A during the gas making period; in this example it is 1.25 feet persecond. After the temperature has dropped below a good gas-makingtemperature in zone B the run is discontinued and the cycle is repeated.

Variations in the procedure can be made in re forming hydrocarbons by:

(a) Altering or varying bon ratio in the feed during period.

(b) Introducing a fluid stream containing steam oxygen into the fuel bedduring the gas-making period, into a zone between top and bottom asthrough bustle pipe l5 into zone B.

(0) Introducing hydrocarbon material zone 13 during the gas-making run.7 (d) Extending the run period by introducing a combustion supportingfluid at the bottom of the fuel bed during the gas-making period as byopening valve 4 or 6.

(e) Substituting CO2 for some of the steam admitted into zone A duringthe gas-making run.

(1) Changing the relative rates of blasting during the air-blast andgas-making periods.

(g) Changing the temperature range for gasmaking.

(h) Making a plurality of these changes.

It isunderstood that fresh solid fuel suitably the gas-making into thegas-making run, cal

the steam-hydrocar- Tall . run only, when so'desired; the

fine and preferably free from very fine dust is fed into the generatorfrom hopper 1 through valve 8 at a rate adapted to maintain thedeep bedin the generator. Gas can be made having a higher calorific value byintroducing enricher through valve 2% during the gas-making run or therun can be prolonged so that the methane content of the gas made ishigher. This latter is not economical when re-forming methane but it iseconomical when higher-molecular-weight hydrocarbons are re-formed.Similarly, powdered coal may be supplied to the generator durthegas-making period and is best accomplished by introducing it into zoneB. No special connection is shown for feeding powdered coal but valve3.4 may be'considered as a control valve for this purpose. Apretreatedsubstantially deashed or low-ash coal should be used and it may beintroduced during a portion of the gas-making fore part of the run ispreferred.

EXAMPLE 4 Rea-forming hydrocarbons without the use ofsolid fueLbutemploying technique which otherwise is substantially like that inExample 3, referring to Figure 1 In this example coarse silica sand wasfluidized in the generator instead of fine size solid fuel. The silicasolids are heated to a high temperature of the order of l800 to 2000 F.by burning fuel with air in the bed of sand; the fuel may be introducedalong with air by opening valves 4 and 30 at the bottom of the bed andthis fuel may be gaseous, liquid or a powdered solid; the fuel may beintroduced through valve la-A when desired. The velocity oi the gaseousstream passing up through the generator during the heating period issuch that the sand is fluidized and the bed density is greater in zone13 than in zone A. As in previously presented examples the rate ofsettling in the packed portion of the reactor, when a sudden decreaseoccurs in the superficial velocity of the fiuidizing fluid; is slower ina packed zone than in a zone free of packing. With sand having particlescloselysized and approximating 40 mesh size, it has been found that thebed density in zone B is about 82 pounds when the superficial velocityof the fluidizing stream is 1.5 feet per second, it is 70 pounds at 3.0feet per second and approximately 66 pounds at 3.5 feet velocity offluid now therethrough. However, in the packed region the bed densityalso decreases as the velocity of the fluidizing agent increases, but ofmajor importance in this case is the fact that at a given fluid velocitythe bed density in a packed zone decreases as the size of the pac ingdecreases, namely, as the size of the intersticial spaces decrease. Whenzone A contains lil6h Berl saddles the bed density of the sand is about35 pounds with a gas velocity of 3.5 feet per second and about 62 poundsat a velocity or 1.0 foot per second;

' with -inch saddles the bed densities for velocities of 1 and 3.5 feetper second flow '01 fluidizing gas are, respectively, 55 and 27 pounds,whereas with large size saddles, 2-inch and larger, the bed densityapproaches but is somewhat lower than that which occurs in a zoneThe-fuel used during this heating period may be quite completelyconsumed in zones A and B, liberating the maximum amount of heattherein; this heat is largely absorbed by the fluidized sand in thesezones. This operation differs from. simifreeof packing.

approximately as follows:

larly blasting a fixed bed because in the present case the solids (sand)are quite uniformly heated in these zones, A and B, as are also thesolids of which the packing in zone A are comprised, whereas with astationary bed the solids gas-making and a considerable amount of heatis stored in the packing in zone A, the supply of heating fuel and airis discontinued by closing valves IB-A, 4 and 30 while simultaneouslyopening valve 5 and introducing steam into the fuel bed. Immediatelythereafter the hydrocarbon to be re-formed is introduced by openingvalve 33 and the stack-gas valve is closed simultaneously with theopening of the gas-offtake valve 14. The steam and hydrocarbon are wellmixed before they pass as a common stream into the bed of fluidizedsand. The gas-air velocity (superheating period in zone lower because ofthe increase in volume due to re-forrning reactions which are typifiedby EquationsB, 4, 5, 6 and 7 as follows: (3) CHlj+H2O=CO+3H2 The beddensity is approximately 68 pounds in zone B during this gas-makingperiod. After the temperature in zone A falls below a level satisfactoryfor making gas, as indicated by the use of thermocouple 21, the supplyof hydrocarbon, natural gas in this example, is shut off by closingvalve 33. After a few seconds the steam 'valve is closed simultaneouslywith the opening of valves 4 and to repeat the heating operation. ValveI0 is now opened simultaneously with the closing of valve I 4 and thecycle is repeated. The composition of the gas depends largely on thetemperature maintained in the reaction zones A period or, expresseddifferently, it depends on the cycle chosen. If the gas-making run isprolonged and the temperature decreases appreciably in zones A and B,more methane will pass through the generator undecomposed and the CO2content of the gas made will increase; likewise the calorific value willincrease. In making gas at the high temperature range 1950 to 2000 F.,the composition of the re-formed gas will be Volume percent CO2 4.6 CO19.0

Illuminants Trace CH4 2.9 C2H6 0.0

and 13 during the gas-making at least a portion of 4140 cubic feet 20pounds 370 cubic feet Somewhat above 400 F.

Blasting with air and fuel gas 3 Blasting with steam and natural gas 2 Afew seconds for purging the blast gas is included in the gas-makingperiod with methane. (b) Make occasional or regular introductions duringthe gas-making period particles stick together; perature limit is about2000 F. for particles of 20 mesh size although higher temperatures mayprevail with larger size fluidized solids.

this tem- Hz and CO substantially as described, namely the gas-makingfluids into the reactor adjacent the bottom of the bed of solidsconfined therein, which fluids comprise steam and a hydrocarbon, or ahydrocarbon and oxygen with or without steam, or a powdered solid fuelwith an oxidizing agent, and then during the gas-making periodintroducing a carbureting material into an upper zone, such as zone B,by opening supply valve 24. This carbureting material may be a gaseousor liquid material typified by propane, petroleum refinery gas, butane,gasoline, naphtha, gas oil, fuel oil or other hydrocarbon substance. Anycarbon depositing on the fluidized solids will ultimately be oxidized asthe solids circulate through the system, that is, through zones A and B.The resulting gas may be of predeand vice versa,

" site direction.

7 1i termed calorific standard suitable for distribution as city gas. r

(e) Vary the mean size of the packing, that is, change relative sizes inthe different zones A, C and D of the Figure 1. For a given superficialvelocity of the gasiforrn fluids in the generator the actual linearvelocity in the void spaces (interstices) in the packed zone variesinversely as the size of the packing solids. EX- pressed differently,with a given stream superiicial velocity through different packed zones,

having different size packing, and fluidizgiven mass of solids in thepacked zones,

each ing a there are less fluidized solids per cubic foot in the zonecontaining the smallest size packing the zone containing the largestsize packing confines the most dense bed of fluidized solids. Thus, inzone A during a heating period, it is frequently desirable to burnthefuel therein as completely to CO2 and H20 as possible; the lowdensity bed may be provided for this purpose by adjusting the size ofthe packing in zone A and the velocity of the combustion supportingfluid therethrough. Zone A is, among other things, during the heatingperiod. Zone C is a temperature equalizing zone; in it final gas-makingreactions are largely completed and a greater bed density of thefluidized solids is usually desired,

hence, larger'size-packing may be used. These variables may be adjustedaccording to the kind of-gas'to be made, the raw materials used, and therelative depth of zones A and C. On the other hand, when solids, such assilica, are fluidized in zone A and the. heating is accomplished byburning fuel with air, each introduced from without, it is necessary tohave plenty of fluidized solids in zone A for the purpose of heattransfer and for preventing the packing solids from becoming overheatedin the bottom portion of that zone; this may be accomplished mostreadily when the size of the packing is not too small. Again, onefrequently can uselarger size packing in the lower portion of zone A andsmaller size in-the upper portion thereof with beneficial results andthis also applies to the upper zones C and D. V I

(f) Operate quite continuously, maintaining high gas-making temperaturesthroughout the fluidized bed, removing the hot gas and passing itthrough a heat exchanger to generate steam and using the steam thusgenerated to make gas in the generator.

(or) Vary. the diameters of Zones C and D relative to each otherdifferent bed densities will prevail with common sizepacking. in A, Band C or so that a chosen density will prevail in either zone because ofthe effect of change of diameter on superficial velocity of the gasstream in a particular zone.

EXAMPLE 5.-EXOTHERMIC REACTION The'productio of enriched gas byreactions of CO with Hz, with particular ure 2 The reactions'which aretypical of the production of methane-of thisexample are:

(8-) CO+3H2=CH4+H2O (exothermic) (9) 2CO+2Hz=CH4+CO2 (exothermic)reference to Fi These reactinsare reversible, high temperatures favorthem progressing from right to left, whereas at'low temperaturesthey-progress the oppo- An increase in pressure favors a heat storagereservoir w and relative to A and B so that presence of a catalyst.Increasin the pressure in generator l favors the production of CH; byaltering equilibria conditions. In fact, the reactions occur'when thestream containing CO and H2 is contacted with hot active carbon attemperatures of 1000" to 1300 F. The difficulty experienced heretoforein promoting such reactions in a fuel bed has been the lack of accuratetemperature control in the fuel bed, there is ordinarily a hot zone,developed by virtue of "the exothermic nature of the reaction, whichtends to reverse the reaction. With reference to Figure 2 the procedureis as follows:

Coarse grain catalyst which may initially comprise iron oxide isfluidized as a deep bed in generator l by passing'combustible gas uptherethrough by opening valve 30. Combustion is promoted in thisgasstream using air introduced into i through valve 4, the gasesresulting therefrom are. conducted out through offtake 9 and valve it asdescribed above. After the temperature indicated by means ofthermocouple 21 is about 1200 F., the air valve 4 is closed and a gascontaining appreciable amounts of C0 and Hg is passed up through thecatalyst atafluidizing velocity by opening valve 34. Now valve I0 isclosed and simultaneously valve I4 is opened and the stream containingreaction products is removed through conduit ltandvalvel l. Thetemperature in the catalyst mass will tend to increase and it isnecessary to keep the tempera-'- ture of the catalyst mass within limitsin order to produce the optimum amount of hydrocarbon reaction products;The limit varies with the nature of the catalyst or contact solids used,althrough there is a definite status of the Reactions 8 and 9 for anystated temperature and pressure at equilibrium. Since equilibrium is notalways reached in making rich gas from CO and H2 at commercial streamvelocities, other factors must be considered. In placeof, or associatedwith an iron catalyst, a. granular or fine size active carbon such aslignite, char, carbonized sub-bituminous coal or other carbonaceoussolid fuel may be used as the fluidized solids. In thiscase it ispreferred to operate with a temperature in the bed in B and C at about1200 as with active catalyst a lower temperature is preferred, namely,about900 to 1100 F. When carbon is the catalyst it is believed somereaction of hydrogen with carbon occurs such as is shown by Equation l0:

bed density is lower for a given superficial velocity C+2H2=CH4(exothermic) j as pressure increases.

Although high pressures favor the desiredpro- "duction of methane itwill be noted thatthe ret0 1400 R, wherelower: temperatures, it

Thus, the hot particles 13 action of Equation 11 is also favored by anincrease in pressure:

(11) 2oo=co2+c The gas stream containing reaction products is cooled tocondense water and other condensthe process steam required allowing forcustomary losses can be produced by utilizing the available excess heat,namely, the methane. Simple means for accomplishing this are shown inFigure 2 which employs a water an upper zone of the generator, whichzone confines fluidized, smalland preferably. above also by a packedsection. of solids (fluidized solids) In this example (Example 5), thepacking in zone A functions as a preheating zone, bringing the reactantsup to reaction temperature and the velocity of fluid flow through zone Ais such that the bed density is low, lower than in zone B?" The zone Cis large so that there is of the fluidized solids in zones appreciablemixing B, C and F. When again; they remain on top until consumed,whereas the sand particles circulate up and down in ebullient motionbeneath any carbonaceous solids which may be present.

It will be understood that in making combusheat of formation of tiblegas by methods such as have been described in the foregoing, packingmaterial in the packed zones regularly shaped solids of much greatersize than the solids which are fluidized; these solids are not pouredsuch as checker bricks are commonly placed in the gas-makingcarburetors. With this type of packing the channels through the packedmasses are regular, the gases passing through the packed masses passthrough a more or less tortuous course but through regularly providedchannels.

The advantage of employing packing of this pare channeling clue willprovide the desired free space and tortuous pass for the fluids. Onesuch packing material has been described in a U. S. patent previouslygranted to me. The size of the packing solids might vary in thedifferent packed zones in aceffect desired, being chosen cording to theconditions of operation as outlined. In a pending application, SerialNo. 582,- 692, filed by me March 14, 1945, now Patent No. 2,503,291,dated April 11, 1950, a different procedure for creating a stratifiedbed of fluidized solids was shown; that procedure can be employed inconjunction with the operation of the generators of the figures in thiscase when of different density may be fluidized in the generator whendesired; the denser solids tending to form a bottom layer. In practicingthis the inventor has found that when coarse silica and air in thiscase, the mixture of the solids is fluidized without separation. Whencombustion is promoted in this bed the solids may be heated to a hightemperature. Now, when steam is passed up through the bed at a lowervelocity the silica it is preferable to employ as.

a'g-cenavez particlessegregate as a lower: stratum and the: silicaparticles: to y the up through the upper' beds of th'e'kind describedhave vnotthus been; used heretoiore', so :far as I am aware, because of;blow-over difficulties whereby fines are entrained.

' pocketsof: gas. 1

in the gas stream. and whereby pass through thebedwithout making good:con.- tact with 1 the .fluidizedsolids'.

make possible the usev of deep. beds; Reference.

has' been made to aplurality of layers of checker. bricks but it ispossible: to

which should extend from above the bottom of the top of the bed; this isthe major gasiform reactants are introduced-entirely at the bottom ofthe bed. The mass ofarranged and spaced checkers, in the single deep thespacing or channels.

layer, may be such that are-not of uniform. dimensions throughout butmay be greater at the top, bottom or middle zone, toprovide a chosenbeddensity condition; How

ever, it is usually preferably to have the top-zone bed-density suchthat a minimum amount of entrairnnent of fine solids in the stream ofreaction products occurs.

Having described my invention so that one skilled in the art canpractice it, making variations andmodifications not given in thespecific examples, I claim:

1. The process of making combustible gas comprised'of CO and'l-lz fromreactants adapted to yield said'CO and H2 by reaction'at elevatedtemperatures, in an elongated upright generator hav ing a deep massof'checkerwork confined therein as apervious stratum extending across itbetween the top and bottom thereof, comprising, ing a deep body offinely divided solids insaid generatorin part in the intersticial spaceof said mass and also above said mass, densely fluidizingthe thusdisposed solids as a deep, single, substantially stationary, a welldefinedtop level in said generator above said mass, by passing'agasiform stream initially containing a combustion supporting fluid and afuel upwardly at a particular fluidizing velocity through said bed ofsolidsand' through said intersticial space, promoting combustion ofsaidfuel in said stream in said bed thereby heati'ngboth the said solids andsaid checkerwork toa reaction temperature below about 1800 FL,discontinuing the heating operation after the reaction temperature hasbeen reached in said bed, then similarly passing a gasiform streaminitially containing steam and at least one combustiblereaotant upwardlyat a superatmosphericpressure through said" bed at a velocitythat'maintains said solids in said densely fluidized state in said bed,thereby making said combustible gas in the latter stream in said bed;anddischarging thelatter gas in said latter stream from above said bed'andrecovering it, meanwhile confining said solids in said bedin saidgenerator substantially as a permanently retained body; said particularvelocity being such that top to bottom circulation of" said' solids insaidibed isJinhibited.

The checker bricks,v

employ one deep layer adjacent but preferably bedto substantially theused-to best advantage when disposcontinuous" bed, having Ythus'disposed solidsas' a deep,

particular law 2000?" R, discontinuing the after reaction temperaturehas beenvreached in:

2: Thezprocess of -.-making, combustible gas; by:

reacting gas-making substance at elevatedtem-- peratures in an upright,=elongated generator having a deep mass ofcheckerwork confined thereinasapervious stratum extending across it between. the'top and-bottomthereof, comprising, disposing:

aldeepbody' of finely divided solidsin saidv generator in'part in:theinterstitial space of said mass: densely fiuidizing the" and:alsoibelow said mass,

single, substantialcontinuous bed'havingawell defined top level tinsaid;generator,- by first :passing a gasiform streaminitially containinga combustion'supportingxfluid and a fuel upwardly at a ly' stationary,

solidsand through saidinterstitial space, promote ing: combustion of'said fuel in said stream in. said: the said solids and bed therebyheating both saidicheckerwork toa reaction temperature beheatingoperation said' bed, then similarly passing a gasiform stream initially.containing steam and at leastone combustible reactant selected from coalupwardly under through said bed from bustible-gas in the latter streamin said'bed, dis-- charging the latter gas insaid latter streamandrecovering it, meanwhile confining said solids in said bedsubstantially as a permanentlyretained body; said particular velocitybeing suchthat top to bottom circulation" offsaid solids in said bed isinhibited.

3. The process defined in-claim 2 in which thegas-making fluid streaminitially comprising steam and a combustible reactant also'initially.contains oxygen.

' 4. The process defined in claim 2 in which the gas makingfluid' streaminitially comprises both References Gited in the file of'this patentUNITED STATES PATENTS Number Name Date" 1,840,649: Winkler et'al. Jan.12, 1932 1,857,799. Winkler May 10, 1932 2,359,310 Hemminger Oct. 3,1944 2,363,274; Wolk. etral. Nov. 21, 1944' 2,443,675 Atwell June 22,1948 2448;290': Atwell Aug. 31, 1948 2,472,502: Tyson June '7, 19492,494,337 Hemminger Jan. 10, 1950 7 2,515,156; Jahnigetal. July 11',1950 2,533,026; Matheson -1 Dec; 5; 1950 FOREIGN PATENTS Number; CountryDate 321,422 Great-Britain Nov. 4, 1929 498,094-

Great-Britain 1 Janis; 1939 fluidizing velocity through saidbed of thegroup which, consists=of gasiformhydrocarbons and powderedsuperatmospheric pressurebeneath it at a velocity that-maintainssaid'solids' in said densely fluidized' statein said bed therebymakingsaidcom--

2. THE PROCESS OF MAKING COMBUSTIBLE GAS BY REACTING GAS-MAKINGSUBSTANCE AT ELEVATED TEMPERATURES IN AN UPRIGHT, ELONGATED GENERATORHAVING A DEEP MASS OF CHECKERWORK CONFINED THEREIN AS A PREVIOUS STRATUMEXTENDING ACROSS IT BETWEEN THE TOP AND BOTTOM THEREOF, COMPRISING,DISPOSING A DEEP BODY OF FINELY DIVIDED SOLIDS IN SAID GENERATOR IN PARTIN THE INTERSTITIAL SPACE OF SAID MASS AND ALSO BELOW SAID MASS, DENSELYFLUIDIZING THE THUS DISPOSED SOLIDS AS A DEEP, SINGLE, SUBSTANTIALLYSTATIONARY, CONTINUOUS BED HAVING A WELL DEFINED TOP LEVEL IN SAIDGENERATOR, BY FIRST PASSING A GASIFORM STREAM INITIALLY CONTAINING ACOMBUSTION SUPPORTING FLUID AND A FUEL UPWARDLY AT A PARTICULARFLUIDIZING VELOCITY THROUGH SAID BED OF SOLIDS AND THROUGH SAIDINTERSTITIAL SPACE, PROMOTING COMBUSTION OF SAID FUEL IN SAID STREAM INSAID BED THEREBY HEATING BOTH THE SAID SOLIDS AND SAID CHECKWORK TO AREACTION TEMPERATURE BELOW 2000* F., DISCONTINUING THE HEATING OPERATIONAFTER REACTION TEMPERATURE HAS BEEN REACHED IN SAID BED, THEN SIMILARLYPASSING A GASIFORM STREAM INITIALLY CONTAINING STEAM AND AT LEAST ONECOMBUSTIBLE REACTANT SELECTED FROM THE GROUP WHICH CONSISTS OF GASIFROMHYDROCARBONS AND POWDERED COAL UPWARDLY UNDER SUPERATMOSPHERIC PRESSURETHROUGH SAID BED FROM BENEATH IT AT A VELOCITY THAT MAINTAINS SAIDSOLIDS IN SAID DENSELY FLUIDIZED STATE IN SAID BED THEREBY MAKING SAIDCOMBUSTIBLE GAS IN THE LATTER STREAM IN SAID BED, DISCHARGING THE LATTERGAS IN SAID LATTER STREAM AND RECOVERING IT, MEANWHILE CONFINING SAIDSOLIDS IN SAID BED SUBSTANTIALLY AS A PREMANENTLY RETAINED BODY; SAIDPARTICULARLY VELOCITY BEING SUCH THAT TOP TO BOTTOM CIRCULATION OF SAIDSOLIDS IN SAID BED IS INHIBITED.